Invoice line is not saved when linked to POL

Overview: An invoice line that is not linked to a POL is not saved when a link to a POL is added.

Pre-requirements: Invoice is created with one invoice line that is not linked to any POL (e.g. imported via data-import and no matched POL found)

Steps to Reproduce:

1. Log into some FOLIO testing
2. Go to Edit invoice line
3. Select POL in lookup to link
4. Press save button

Expected Results:

Invoice line is saved with POL reference

Actual Results:

Request throws 404 error with message "The purchase order line record is not found"

Additional info:

If user clicks Save button again (after getting error) Invoice line can be saved